Ensure comparability and emphasize differences in directly grokable way for all formats (currently only ATOM and JSON)

The current revisions of [OData ATOM Format Version 4.0](https://www.oasis-open.org/committees/download.php/48588/odata-atom-format-v4.0-wd01-2013-03-19.doc) and [OData JSON Format Version 4.0](https://www.oasis-open.org/committees/download.php/48589/odata-json-format-v4.0-wd01-2013-03-19.doc) might be easily enhanced for the reader in performing structural transformations and/or add examples to ensure comparability and emphasize differences in directly grokable way for the form that open data uses in message instances (request and repsonse the like).

1. I think structuring the documents in a directly similar open data oriented way should be a good first step.
2. Highlight the (possible) gotchas when changing from one format to another could be described in all places, where information might get lost or needs complicated transformations on part of the client and/or server.
3. Share the same open data example content in 'format#xyz' form, so that the reader has a spot on for the format and not has to blend out the content when comparing the formats.
4. Show - besides noting conventional suppression policies per format - how to explicitly set default values, so that it is clear for any case.
5. Indicate, where a user or implementer using ATOM, JSON for years should be aware of unconventional usage of the format in OData context